This invention relates generally to laboratory evaporation apparatus and, more particularly, to apparatus for automatically and sequentially isolating a solid in a sample by evaporating its liquid content, reconstituting the residue as a liquid by adding a solvent, and again isolating the solid by evaporating the added solvent.
In many laboratory applications, it is desirable to transfer a solute from one solvent system to another solvent system. For example, this procedure is used frequently in liquid chromatography where a solution, perhaps a liquid fraction obtained from one chromatographic procedure, can be more specifically analyzed by use of a different solvent. In the past, it has been common to place the first solution into a tube and, using a gas sparge tube, or cannula, contact the solution with sufficient drying gas to remove the unwanted liquid.
An improved system for achieving laboratory evaporation is disclosed in U.S. Pat. No. 4,707,452. That system provides a receptacle for liquid being processed and gas feed means to supply carrier gas into the receptacle such that the gas follows a path downwardly along the receptacle wall until it reaches the material to be treated. This procedure serves to leave a relatively free central path in the receptacle through which the process gas, now laden with any material being evaporated, may proceed upwardly through the central portion of the volume enclosed by the walls of the receptacle. Because the gas leaving the receptacle is not much diluted by mixing with the incoming gas, it is more sensitive to analysis by any number of procedures. However, after evaporation is completed, much of the residue usually is spread in a thin film over the inside surface of the receptacle. Full residue recovery, therefore, generally requires one or more solvent adding reconstitution steps followed by further evaporation. Such procedures are time consuming for highly trained laboratory personnel.
The object of this invention, therefore, is to provide an improved, more efficient apparatus for accomplishing various types of laboratory evaporation procedures.